The present invention relates to thermoplastic or thermoset skin cladded polyurethanes having an improved surface appearance. The present invention particularly relates to thermoplastic skin cladded polyurethane foams having an improved surface appearance.
Polyurethane based polymers have long been known to be useful in preparing many products. For example, rigid polyurethane foam can be used in products such as pipe insulation, flotation devices and appliance insulation. Flexible polyurethane foam can be use in automotive seat cushions, toys and furniture manufacture. Semi-rigid polyurethane foam can be used to prepare products such as automotive headrests, dashboards and armrests. Reinforced rigid polyurethane foams are increasingly being used to prepare lightweight automotive door panels, seat backs and the like.
Polyurethane surfaces are sometimes neither suitable nor desirable for certain applications. For example, a polyurethane foam surface may not be durable enough or not aesthetically appropriate for an automotive interior application. One means of avoiding this problem while retaining the benefits of using a polyurethane in such applications is by using a plastic skin cladded polyurethane. For example, UK Patent Application 2 148 786 A discloses preparing a bathtub having a preformed acrylic shell and a polyurethane foam reinforcing layer. U.S. Pat. No. 4,784,904 to Wood, et al., discloses preparing an object such as a sink have an acrylic shell and a polyurethane foam reinforcing layer.
Similarly, flexible foams and semi-flexible foams can be prepared with plastic skins. However, preparing cladded polymers, particularly cladded foamed polymers is not always trouble free. One such problem occurs when adhesion between the polymer and the plastic skin fails. Gas can accumulate in the space between the skin and foam and form a raised area on the skin surface commonly called a "blister". Such blisters are serious aesthetic defects and can cause a part to be rejected which increases waste and lost production time. It would therefore be desirable in the art to prepare cladded polyurethane polymers which do not display this blistering phenomena.